Assessment of atmospheric lead contamination of banks soils using soils tamarisk grove: case study of the Kebir-Rhumel (Algeria)

In order to know the role of the tamarisk grove in the soil contamination by lead (Pb) fallout, ten stations were randomly selected along the Kebir-Rhumel wadi which skirts a heavy traffic road. In each site, the sampling stations were chosen so as to contain a vegetation plot nearby a bare plot. All the stations were localized on the road side. Two soil's samples were taken in the middle, the road and wadi side of each plot. Tamarisk leaves were the object of an average sampling. Pb concentration was measured, by (ICP-OES) in washed (0.53 mu g.g(-1)) and unwashed leaves (1.23 mu g.g(-1)), and in total extracts of soils (18.0 mu g.g(-1)), which were also the object of organic matter (OM), pH, electrical conductivity (EC), total CaCO3, cation exchange capacity (CEC) and particle sizes analysis. Significant differences were noted between washed and unwashed Pb leaves contents, suggesting an atmospheric contamination source, apparently from the road traffic. Pearson correlation coefficients indicate that total Pb soil contents were significantly and positively related to OM (3.30 %) and clay (10.20 %) in vegetation plots, and to pH (7.82), CEC (17.60 cmol(+).kg(-1)) and silt (30.90 %) in the bare plots. Analysis of variance (ANOVA) and Scheffe's test reveals Pb, OM and clay contents in vegetation plots (especially in the middle of tamarisk grove) are significantly greater than in bare plots. The results show that the tamarisk grove, through the generated OM rates and the clay catching, would allow the retention of Pb in the soils, thus its mobility will decrease towards the stream water.